What does the symbol "$\triangleright$" mean programming language semantics? I've seen it in the context of datatypes in and the evaluation of expressions in environments.
For example :
$$tenv \triangleright erht \implies tval $$
$$tenv[tval/x]\triangleright ebody\implies t\,.$$
Here, $tenv$ is an environment and $ebody$ is the body of some expression.